I'm reviewing Sapiens: A Brief History of Humankind by Yuval Noah Harari one page at a time.
So far, what I've taken on may be characterized as "petty and annoying mistakes"--especially to people outside the field of paleoanthropology who have no personal or professional relationship with the details.
I get it. Who cares about nuances of skull anatomy and beginning/end dates of the different extinct hominin species. If everyone thought that stuff actually mattered, then everyone would know paleoanthropology like a pro.
But if I believed that all I was doing here was quibbling over details, then I wouldn't be doing it. The last thing I want to do is point out meaningless, harmless errors in someone's book. I got a tummy ache just thinking about it.
What I hope I'm doing by pointing out these errors is revealing that, so far, the details don't really matter. And that matters!
Some, most, or maybe all (stay tuned... we're not through it yet...) of the arguments in Sapiens that are based in human evolutionary history are not based in evidence. That's why there's no need for citations and that's why hominins and their places in time can be misrepresented (as seen on pages 6,7,and 8).
Why include those details in Sapiens if they don't matter?
Just presenting the fact that humans evolved, period, whether the presentation is 100% accurate or not, establishes the fact that humans evolved, period. You could read these early pages of Sapiens as if they're saying: Oooh. Look at these fossils! Now hear me out...
As long as there have been fossils, the fact that we evolved over deep time has been grounds for making up stories about our ancestors and what we carry with us, today. Harari's just following tradition, and with gusto.
Page 9
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| I want to acknowledge the glare on the shiny paper they used. If anyone's been actually reading along, then I apologize for the frustration you must be feeling. But I've only been sharing the pages to show my mark-ups. I've been writing these posts as if no one is reading along. I've been trying to make my posts make sense without anyone needing to read the book, too. I hope it's been working ... |
The last graf on page 8 kick-starts this section. I ran out of time last time and decided this was the better place to deal with it.
We're in the section called "The Cost of Thinking". Harari starts (back on page 8) by claiming that mammals weighing 130 pounds have brains that are 12 cubic inches. I'm not chasing that down. I can barely muster the fucks to convert 12 cubic inches into something I understand. For brain volume, I'm used to dealing in cubic centimeters (cc) or milliliters (ml) and, for brain mass, I'm used to dealing in grams (g). They probably translated the units into cubic inches for the English speaking readership. It's easy enough to use an online converter. Twelve cubic inches is about 200 cc. That's fine. I'm not going to spend my morning figuring out where he may have gotten this estimate, but it's not wacky so we'll just keep going. He says the earliest members of the genus Homo had brains that were roughly 600 cc. Yes, fine. That estimate comes from measuring the space within the fossil cranial bones. And sapiens? Our brains are like 1200-1400 cc. Yes, fine.
Now to page 9, proper.
Oh, forgive me. The first sentence showcases two of my peccadilloes.
"That evolution should select for larger brains may seem to us like, well, a no-brainer."
Evolution cannot select anything. Neither can natural selection! Those phenomena are not agents. They are processes that are happening, always. They never don't happen. Evolution is the only way life works and anything that lives can be considered adaptive (yes, that's what I said, no not everyone would agree, no I'm not an idiot, no they are not either). But nothing and no one is doing evolution to life. Life is evolution.
He also asks, "Why are giant brains so rare in the animal kingdom?" As if the cats and frogs of the world don't have giant brains. Relative to Earth's history they sure do. This life thing is an ongoing thing. Cats and frogs are large-brained and absolutely brilliant. I'm not so sure if from, say, an omniscient, god-like point of view over the entirety of space-time, we could even claim that our brains are so much larger than cats' and frogs'. But he's entitled to his perspective.
These are fine estimates of the metabolic cost of brains, I think. They've probably been refined by now but they aren't going to be far off, I don't think. Our big brain costs a lot of energy to grow and to run. Yes.
Now it gets interesting...
"Archaic humans paid for their large brains in two ways."
It's missing a "likely" or "probably" or "could have" or... any nuance.
"Firstly, they spent more time in search of food."
There's literally, no way of knowing. It's totally make-believe stuff about hominin behavior.
"Secondly, their muscles atrophied. Like a government diverting money from defence to education, humans diverted energy from biceps to neurons."
Again, there's literally, no way of knowing. It's totally make-believe stuff about hominin physiology and soft tissue anatomy.
I'm not saying he doesn't know this. He's offering what scientists have said (but not citing them). Without any nuance, this discussion sounds a lot more fact-based than it is.
Next, he points out the sacrifice (to survival and reproduction) that giving up physical strength for increased thinking strength would have been. He says it's, "hardly a foregone conclusion" that trading away muscle for neurons was a good thing. Weighing the costs/benefits like this is a routine aspect of human evolutionary storytelling. But if you have no way of knowing if the premise (like giving up muscles for brains) is true, then what's the use of wondering how the heck it could be?
We're here. Big brains and all. We exist despite any real or imagined burdens our big brains bestowed up on our ancestors.
Ah, the joking about shooting chimps with guns. It's sardonic and I get it. He really despises humans, at least sometimes, and it leaps off the page. I despise humans who shoot chimps too. When you're a paleoanthropologist you find yourself in the strangest situations, like, sitting in the back room of a museum, pawing through drawers of gorgeous chimpanzee, gorilla, or bonobo bones that only got there because some dead old rich guy killed them on safari, including the babies, because they'd be dead anyway, without their mothers. Ah, science...
Onto the third graf. Here's where I feel so defensive for our hominin ancestors. Is he ragging on them for being idiots? They had bigger and bigger brains since 2 million years ago, "but apart from some flint knives and pointed sticks, humans had previous little to show for it."
Gasp. How dare you! It's true, culture and technology had to start somewhere. But I think we're maybe overlooking a very important obstacle to our ancestors' ability to show us what their brains could do. It's the problem of preservation.
(Sorry. I think I might have tripped over the same kinds of metaphors he was using on earlier pages when he made history and a whole species into keepers of secrets. What can I say, I fell over.)
"What then drove forward the evolution of the massive human brain during those two million years? Frankly, we don't know."
Correct. Hooray! We don't!
I wonder if this attitude will carry forward.
The last graf is about bipedalism. You can see further if you're upright. Yes. You can throw stuff. Yes. You can signal to others with your arms and hands. Yes. You can make and use sophisticated tools. Yes.
"The more things hands could do, the more successful their owners were": NO WAY OF KNOWING IF TRUE.
Why point this out? Doesn't it seem obvious that our bipedal bodies, including our awesome, freed hands, are designed by natural selection? It does. And they certainly work or they wouldn't exist, but imagining each and every aspect of our bodies as the driver of our ancestors' evolutionary success doesn't make any sense. At some point it just becomes creationism. We are, and our ancestors were, entire organisms. If every single thing about them was the driver of their enhanced survival and reproduction... if survival and reproduction hinged on every single way their bodies varied compared to each other and to their ancestors... then wouldn't the whole system fail? Way too house-of-cardsy.
(And that's why when you fight creationism with hyper-adaptationism, the clever creationists are like "that's impossible!" I'm not speaking from experience. I don't fight creationists. But I've seen enough fights to know.)
Ahhhh, there's no space or time to dig into the problems with adaptationism. And now's a horrible moment to try, given how big brains and bipedalism are considered to be quintessential human adaptations. I'm not touching those. They certainly are nice!
But the point is, as usual, we're being presented with a confident and simple story that doesn't follow from either the evidence or 21st century evolutionary theory.
Page 10 is next. It's got the obstetrical dilemma on it. (Deep breaths. Send chocolate, beer, and puppies.) To be continued...
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